Oh wow!

I remember these bufffer cards. They were all over the place, a friend of mine built one from schematics in a German C64 magazine.

The idea was that these cards accept the data faster than your printer can, so that you can continue to work on your computer while the card finishes the printing job in the background. Hard to imagine nowadays, where everything is multi-tasked, but it was a pretty big deal back then. Hardware-assisted multitasking smile

I had totally forgotten that this was a thing.